Alyssa Palombino and sons Francesco, 5, and 5-month-old Mathieu live in a two-bedroom at the Gretsch building, home to an olive oil store and an art gallery. Photo: Imogen Brown(2)

GIVE MY REGARDS TO BROADWAY: South Williamsburg’s new rental development at 11 Broadway has 160 apartments (25 low-income) and approximately 21,000 square feet of retail in its 15 stories. (Imogen Brown)

GUILD TRIP: Retail is booming in the area with notable newcomers like the Gourmet Guild market, which has local produce and an espresso bar in its 3,000 square feet. The store opened up last December on Broadway. (Imogen Brown)

Ayear ago, Alyssa and Mathieu Palombino moved into the Gretsch, the 10-story South Williamsburg building on Broadway between Wythe and Berry that was converted into condos back in the early 2000s. They liked being away from the drama a few blocks north.

Their 1,450-square-foot, two-bedroom, 2 1/2-bathroom condo, which they found with Stefanie Barlow of the Corcoran Group, has an unobstructed view of the East River from its dramatic, oversized windows. And it’s in this apartment that the Palombinos are concentrating on raising their two sons, Francesco, 5, and Mathieu, 5 months.

Alas, South Williamsburg wasn’t going to keep quiet for long.

Just across the street, a 77-unit rental building with commercial space at 53 Broadway has begun rapidly rising and should be finished in 2013. A little bit closer to the water at 11 Broadway, on the corner of Kent Avenue, a 15-story, mixed-income, 160-unit rental development with approximately 21,000 square feet of retail space just got its temporary certificate of occupancy; it plans to have its market-rate apartments filled by December.

Around the corner at 373 Wythe St., an 11-story, 88-unit rental building is well under way and should be finished in March 2013.

And this is to say nothing of the several thousand planned units in the old Domino Sugar Factory, the 11-acre parcel of land off of Kent Avenue that Brooklyn developer Two Trees looks set to purchase after clearing legal hurdles.

But South Williamsburg is also seeing smaller boutique buildings come on the market. Back in September, David Maundrell of Aptsandlofts.com held an open house for the eight-unit 251 S. Third St., where condo prices range from $555,000 to $799,000. He had three accepted offers that same night.

A week earlier, Maundrell had 193 sign-ins at an open house for 112 S. Second St., where prices range from $399,000 to $699,000, and made deals on seven of eight of its condos.

Plus, Maundrell has yet another boutique condo building coming to market this month at 199 S. First St., with 10 apartments ranging from $475,000 to $680,000.

Apartments in the area — both condos and rentals — are fetching prices that would have once been unheard of in prime Williamsburg, much less South Williamsburg.

“It’s definitely Manhattan prices,” says Barlow, who has a one-bedroom available for rent at the Gretsch for $3,500 per month.

A couple of blocks away, at 330 Wythe St., a 1,427-square-foot unit is on the market for $1.5965 million. The Smith Gray building, at 138 Broadway, has a three-bedroom on the market for $1.325 million and two apartments for rent: a one-bedroom for $3,300 and a three-bedroom for $6,475.

What, exactly, drove prices up and developers wild in this part of Williamsburg?

Part of the reason is that the huge amount of housing stock (which everyone assumed would last for decades) in Williamburg’s north side finally got exhausted. And the fact that in 2010 the M train replaced the V train, offering a fresh route to Midtown and the Village, can’t be overlooked.

“When the M turned orange, that was a huge boon to the population,” Barlow says. “It offered a way to get to Midtown without transferring.”

“I have a lot of love for the M train,” says Brittany Flynn, who lives even farther into South Williamsburg on Walton Street. “It’s mostly reliable, and it goes to such good areas — the Lower East Side . . . and it takes me 40 minutes to get to Midtown.”

Flynn, a freelance writer and temp, moved into a two-bedroom that rents for $1,600 per month about a year ago, and her roommate, Mary Balash, moved in a month ago.

“We’re just about five minutes out of reach for our ideal,” says Flynn. Balash and Flynn spend a lot of their free time in the Williamsburg/Greenpoint area, a scene which is slowly expanding its borders south.

A Whole Foods-like grocery store called the Gourmet Guild opened late last year at 110 Broadway. An art gallery and a store exclusively dedicated to olive oil and balsamic vinegar opened in the Gretsch’s retail space.

Not to mention, Alyssa Palombino’s husband, Mathieu, the celebrated chef behind Motorino and the Bowery Diner, has gotten in on the act: He is planning a Motorino on Broadway that is currently waiting for its liquor license.

And nearing completion is a movie theater with stadium seating, Williamsburg Cinemas, opening on the corner of Driggs and Grand. Manhattan eateries like Vanessa’s Dumplings have opened on the south side of Bedford, along with hot spots like the bar/eatery, Potlikker. Art galleries and clothing shops like Eco Closets and jewelry shops like A Thousand Picnics have all gotten in on the action.

Another part of what’s making the area so desirable is that despite the fact that prices have climbed, they still haven’t matched their neighbors to the north.